Merge pull request #916 from compas-dev/random-samples

Random samples of stuff

Author: tomvanmele

CHANGELOG.md

@@ -26,6 +26,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * Added version-based installation for Blender.
 * Added several shape artists to `compas_ghpython`: `BoxArtist`, `CapsuleArtist`, `ConeArtist`, `CylinderArtist`, `PolygonArtist`, `PolyhedronArtist`, `SphereArtist`, `TorusArtist` and `VectorArtist`.
 * Added support for CLR generic dictionaries to the `compas.data` decoders.
+* Added `Graph.node_sample`, `Graph.edge_sample`.
+* Added `Halfedge.vertex_sample`, `Halfedge.edge_sample`, `Halfedge.face_sample`.
+* Added `Halfface.vertex_sample`, `Halfface.edge_sample`, `Halfface.face_sample`, `Halfface.cell_sample`.
+* Added `Mesh.from_meshgrid`.
 
 ### Changed
 

src/compas/artists/meshartist.py

@@ -65,13 +65,13 @@ class MeshArtist(Artist):
     default_color = (0.0, 0.0, 0.0)
     default_vertexcolor = (1.0, 1.0, 1.0)
     default_edgecolor = (0.0, 0.0, 0.0)
-    default_facecolor = (1.0, 1.0, 1.0)
+    default_facecolor = (0.9, 0.9, 0.9)
 
     default_vertexsize = 5
     default_edgewidth = 1.0
 
     def __init__(self, mesh, **kwargs):
-        super(MeshArtist, self).__init__(**kwargs)
+        super(MeshArtist, self).__init__()
 
         self._mesh = None
         self._vertices = None

src/compas/datastructures/graph/graph.py

@@ -314,6 +314,37 @@ def get_any_edges(self, n):
         """
         return sample(list(self.edges()), n)
 
+    def node_sample(self, size=1):
+        """Get a list of identifiers of a random set of n nodes.
+
+        Parameters
+        ----------
+        size : int, optional
+            The size of the sample.
+
+        Returns
+        -------
+        list
+            The identifiers of the nodes.
+
+        """
+        return sample(list(self.nodes()), size)
+
+    def edge_sample(self, size=1):
+        """Get the identifiers of a set of random edges.
+
+        Parameters
+        ----------
+        size : int, optional
+            The size of the sample.
+
+        Returns
+        -------
+        list
+            The identifiers of the random edges.
+        """
+        return sample(list(self.edges()), size)
+
     def key_index(self):
         """Returns a dictionary that maps node dictionary keys to the
         corresponding index in a node list or array.

src/compas/datastructures/halfedge/halfedge.py

@@ -260,6 +260,51 @@ def get_any_face_vertex(self, fkey):
         """
         return self.face_vertices(fkey)[0]
 
+    def vertex_sample(self, size=1):
+        """A random sample of the vertices.
+
+        Parameters
+        ----------
+        size : int, optional
+            The number of vertices in the random sample.
+
+        Returns
+        -------
+        list
+            The identifiers of the vertices.
+        """
+        return sample(list(self.vertices()), size)
+
+    def edge_sample(self, size=1):
+        """A random sample of the edges.
+
+        Parameters
+        ----------
+        size : int, optional
+            The number of edges in the random sample.
+
+        Returns
+        -------
+        list
+            The identifiers of the edges.
+        """
+        return sample(list(self.edges()), size)
+
+    def face_sample(self, size=1):
+        """A random sample of the faces.
+
+        Parameters
+        ----------
+        size : int, optional
+            The number of faces in the random sample.
+
+        Returns
+        -------
+        list
+            The identifiers of the faces.
+        """
+        return sample(list(self.faces()), size)
+
     def key_index(self):
         """Returns a dictionary that maps vertex dictionary keys to the
         corresponding index in a vertex list or array.
@@ -2471,10 +2516,27 @@ def is_face_on_boundary(self, key):
 
     def halfedge_after(self, u, v):
         face = self.halfedge_face(u, v)
-        w = self.face_vertex_after(face, v)
+        if face is not None:
+            w = self.face_vertex_after(face, v)
+            return v, w
+        nbrs = self.vertex_neighbors(u, ordered=True)
+        w = nbrs[0]
         return v, w
 
     def halfedge_before(self, u, v):
         face = self.halfedge_face(u, v)
-        t = self.face_vertex_before(face, u)
+        if face is not None:
+            t = self.face_vertex_before(face, u)
+            return t, u
+        nbrs = self.vertex_neighbors(u, ordered=True)
+        t = nbrs[-1]
         return t, u
+
+    def vertex_edges(self, vertex):
+        edges = []
+        for nbr in self.vertex_neighbors(vertex):
+            if self.has_edge((vertex, nbr)):
+                edges.append((vertex, nbr))
+            else:
+                edges.append((nbr, vertex))
+        return edges

src/compas/datastructures/halfface/halfface.py

@@ -2,7 +2,7 @@
 from __future__ import division
 from __future__ import print_function
 
-from random import choice
+from random import choice, sample
 
 from compas.datastructures.datastructure import Datastructure
 from compas.datastructures.attributes import VertexAttributeView
@@ -268,6 +268,66 @@ def get_any_face_vertex(self, face):
         """
         return choice(self.halfface_vertices(face))
 
+    def vertex_sample(self, size=1):
+        """Get the identifiers of a set of random vertices.
+
+        Parameters
+        ----------
+        size : int, optional
+            The size of the sample.
+
+        Returns
+        -------
+        list of int
+            The identifiers of the vertices.
+        """
+        return sample(list(self.vertices()), size)
+
+    def edge_sample(self, size=1):
+        """Get the identifiers of a set of random edges.
+
+        Parameters
+        ----------
+        size : int, optional
+            The size of the sample.
+
+        Returns
+        -------
+        list of int
+            The identifiers of the edges.
+        """
+        return sample(list(self.edges()), size)
+
+    def face_sample(self, size=1):
+        """Get the identifiers of a set of random faces.
+
+        Parameters
+        ----------
+        size : int, optional
+            The size of the sample.
+
+        Returns
+        -------
+        list of int
+            The identifiers of the faces.
+        """
+        return sample(list(self.faces()), size)
+
+    def cell_sample(self, size=1):
+        """Get the identifiers of a set of random cells.
+
+        Parameters
+        ----------
+        size : int, optional
+            The size of the sample.
+
+        Returns
+        -------
+        list of int
+            The identifiers of the cells.
+        """
+        return sample(list(self.cells()), size)
+
     def vertex_index(self):
         """Returns a dictionary that maps vertex dictionary keys to the
         corresponding index in a vertex list or array.

src/compas/datastructures/mesh/mesh.py

@@ -5,6 +5,7 @@
 import collections
 import sys
 from math import pi
+from itertools import product
 
 import compas
 
@@ -33,6 +34,9 @@
 from compas.geometry import midpoint_line
 from compas.geometry import vector_average
 
+from compas.utilities import linspace
+from compas.utilities import meshgrid
+
 from compas.utilities import geometric_key
 from compas.utilities import pairwise
 from compas.utilities import window
@@ -612,6 +616,40 @@ def from_polygons(cls, polygons, precision=None):
     def to_polygons(self):
         return [self.face_coordinates(fkey) for fkey in self.faces()]
 
+    @classmethod
+    def from_meshgrid(cls, dx, nx, dy=None, ny=None):
+        """Create a mesh from faces and vertices on a regular grid.
+
+        Parameters
+        ----------
+        dx : float
+            The size of the grid in the X direction.
+        nx : int
+            The number of faces in the X direction.
+        dy : float, optional
+            The size of the grid in the Y direction, if different form X.
+        ny : int, optional
+            The number of faces in the Y direction, if different from Y.
+
+        Returns
+        -------
+        Mesh
+            A mesh object.
+        """
+        dy = dy or dx
+        ny = ny or nx
+
+        V, U = meshgrid(linspace(0, dx, nx + 1), linspace(0, dy, ny + 1), indexing='ij')
+
+        quads = [[
+            [U[i + 0][j + 0], V[i + 0][j + 0], 0],
+            [U[i + 0][j + 1], V[i + 0][j + 1], 0],
+            [U[i + 1][j + 1], V[i + 1][j + 1], 0],
+            [U[i + 1][j + 0], V[i + 1][j + 0], 0]
+        ] for i, j in product(range(ny), range(nx))]
+
+        return cls.from_polygons(quads)
+
     # --------------------------------------------------------------------------
     # helpers
     # --------------------------------------------------------------------------

src/compas_plotters/artists/circleartist.py

@@ -68,6 +68,7 @@ def draw(self) -> None:
             facecolor=self.facecolor,
             edgecolor=self.edgecolor,
             fill=self.fill,
+            alpha=self.alpha,
             zorder=self.zorder
         )
         self._mpl_circle = self.plotter.axes.add_artist(circle)

src/compas_plotters/artists/ellipseartist.py

@@ -67,6 +67,7 @@ def draw(self) -> None:
             facecolor=self.facecolor,
             edgecolor=self.edgecolor,
             fill=self.fill,
+            alpha=self.alpha,
             zorder=self.zorder)
         self._mpl_ellipse = self.plotter.axes.add_artist(ellipse)